Consumers have long speculated that organic produce may have greater concentrations of phytochemicals than conventionally grown produce. This makes perfect sense when we consider that phytochemical production is, at least in part, a function of stress on a plant. If a plant is attacked by microorganisms, it will manufacture greater amounts of phytochemicals in an effort to counter the attack. Organic produce receives more contact with naturally occurring microorganisms and pests than conventionally grown food because synthetic herbicides and pesticides are not used. (Source: Becoming Raw)